Possibly over tightening or a bad dive but the feed neck on the clones has been known to have issues. Mine has been bent since the first day of play and others have had cracking issues similar to yours.
MacDev Militia: Clone GTi with Shift Kit, GTi Valve, Pooty Bolt, & Violent Series Trigger
dp Fusion FX with TechT HUSH Bolt & TechT LAW RAM
Sly Pro-Merc Diesel Barrel Kit, dye Rotor with Exalt Speed Feed, & Crossfire SS HPA 68/4500 Tank.